46 results about "Rabi frequency" patented technology

The invention discloses an electromagnetic field near-field imaging system and method based on pulsed light detection magnetic resonance. The system consists of a laser pump optical path, a microwave source, a diamond NV color-center probe, a CCD camera unit, a synchronization system, a displacement scanning platform, control software and a data analysis imaging system. In the system, a large diamond single crystal containing the NV color-center is used as a detection unit, a static magnetic field is used to split a magnetic resonance peak of the diamond NV color-center into eight peaks, the eight resonance peaks correspond to four crystal axis directions <111>, <1-11>, <-111>, <11-1> of a diamond lattice structure, by measuring the Rabi frequency of each resonance peak, the strength of a circularly polarized microwave field perpendicular to the corresponding crystal axis direction is obtained, and through comprehensive calculation of the microwave field strengths in the four directions, the strength and direction of a microwave vector are then reconstructed. Through the microwave near-field high-resolution imaging of a local region of a microwave chip under measurement, the quantitative data can be provided for the failure analysis of the chip.

This invention relates generally to NMR systems for in vivo detection of analytes. More particularly, in certain embodiments, the invention relates to systems in which superparamagnetic nanoparticles are exposed to a magnetic field and radio frequency (RF) excitation at or near the Larmor frequency, such that the aggregation and / or disaggregation of the nanoparticles caused by the presence and / or concentration of a given analyte in a biological fluid is detected in vivo from a monitored RF echo response.

An improved method and apparatus for mode-locking a fiber laser at a pre-selected frequency wherein a doped fiber segment contains a narrowband FBG and an electro-optically tuned FBG, thereby making obsolete the need for an EOM to modulate the laser's wavelength. The present invention also provides a method and apparatus for mode-locking a fiber laser at a variable frequencies wherein a doped fiber segment contains two electro-optically tuned FBG's. The electro-optically tuned FBG may be fabricated by a thermal poling process.

A network analyzer is capable of measuring the antenna return loss in a live cellular network. The network analyzer receives and analyzes the base station transmitted signal to determine which transmit frequencies are active. Based on information relating to the correlation between the transmit frequency and the associated receive frequency, the network analyzer determines the active receive frequencies. An unmodulated source that avoids inclusion of the active receive frequencies is generated by the network analyzer. To fill in the antenna sweep with the previously avoided frequencies, the network analyzer generates another source containing only those avoided frequencies when no calls are active on the avoided frequencies. Alternatively, the antenna return loss on the avoided frequencies is interpolated from the measured frequencies. As a further alternative, the network analyzer receiver determines a nearby frequency to an active frequency, and adaptively measures the nearby frequency as the avoided (active) frequency.

Methods and systems are provided to reduce stimulated Brillouin scattering in high power optical fiber amplifiers. In an embodiment, a seed source includes a narrow linewidth semiconductor laser driven with a current ramp that simultaneously sweeps the optical power and the lasing frequency at a rate fast enough to reduce stimulated Brillouin scattering.

This invention provides a dual-modality system for performing characterization and imaging of tissue, tumors, structures, lesions, and ablations under investigation. Specifically, the invention couples ultrasound technology comprising at least two focused ultrasound beams for vibrating target tissues located at the focal point of the ultrasound beams intersection with a radio frequency system for measuring the response of the target tissues. The ultrasound system vibrates the target tissues while the reflected radio frequency energy is transmitted into the target tissues. When reflected, the main carrier tone of the reflected radio frequency energy is cancelled and analysis is performed on the remaining sideband frequencies.

The device is composed of antenna, matching network outside chip and label chip in radio frequency. The label chip in radio frequency includes bridge type rectification, generation of power source, receiving / transmitting, digital baseband control, and power self-adapting clock etc modules. Module of quantizing voltage supply quantizes voltage, and sets up frequency division number of 1 : n frequency divider. Dividing frequency is carried out based on frequency division number so as to output operation timing of label chip system and decide communication speed rate for returning data. Then, next chip is monitored circularly till all chips are traversed. Applicable to remote radio frequency recognition system, the disclosed method realizes communication in self-adapting variable data rate so as to reach optimum identification distance and identification data rate in operation of identifying radio frequency.

The invention relates to a Ka frequency range miniaturization broadband multimode auto-tracking feed source network. Two polarization degenerate modes of TE21 mode transmitted by center circular waveguide are coupled to four rectangular waveguide by adopting a four-arm circular polarization TE21 coupler. Two four-way polarization degenerate modes of the TE21 mode is combined into two two-way polarization degenerate modes of the TE21 mode by two broadband magic Ts. A left-handed or right-handed circular polarization difference mode is output by a broadband 90-degree electrical bridge. The TE21 coupler center circular waveguide is capable of simultaneously transmitting a TE11 mode. Due to the fact that the TE21 coupler is connected with a broadband circular polarization machine, and two polarization modes of a signal are respectively output from two ports of the broadband circular polarization machine, the Ka frequency range miniaturization broadband multimode auto-tracking feed source network is capable of simultaneously receiving a signal of double-circular polarization and a difference signal, and thereby the auto-tracking function is realized. The Ka frequency range miniaturization broadband multimode auto-tracking feed source network has the advantages of not only simplifying composition of the feed source network, reducing the volume and the weight of the whole device, but also reducing network construction, saving feed source cost and broadening working band of the feed source network.

The present invention relates to a frequency synthesizer and frequency synthesis method based on optical beat technique. The frequency synthesizer mainly comprises an optical fiber laser, a photoelectric detector and a tunable band-pass filter which are sequentially connected and forms frequency synthesis. The present invention generates a series of sinusoidal wave electrical signals with same frequency interval through inputting multilongitudinal-mode laser output by the optical fiber laser to the photoelectric detector and generating beat by laser longitudinal mode in the photoelectric detector. Then the electrical signal of a certain frequency is selected through adjusting the tunable band-pass filter. As the number of laser longitudinal mode is large, the frequency range of electrical signal generated by the longitudinal mode beat is extraordinary wide, and can be changed from megahertz to hundreds of GigaHertz. The frequency synthesizer of the invention has the characteristics of small volume, simple structure, convenient method and wide operating frequency band. The frequency synthesizer and frequency synthesis method belong to the field of modern communication system and instrument measuring.

A linear method for measuring the radiation EMI in GIEM chamber includes putting the object (EUT) to be measured on an turntable in GTEM chamber, determining the relative relation between various axises of EUT and various axises of GTEM chamber, rotating the turntable by alpha angle counterclockwise, measuring 6 data at a certain frequency but different 6 positions, using the linear equations set to find out the equivalent electric and magnetic couple moments, and calculating the radiated field intensify in wide field.

The invention relates to laser technology field and discloses an electro-optic Q-switched pulse laser device with repeat frequencies being variable in a wide range. The electro-optic Q-switched pulse laser device comprises a total reflection mirror, a Q-switched unit, a laser gain unit and an output unit which are connected successively. An electro-optic Q-switched crystal in the Q-switched unit can work in a high-frequency state and can realize output of laser Q-switched pulses with various repeat frequencies through controlling pump pulses applied on the gain unit and Q-switched pulses applied on the Q-switched unit. Compared with the prior-art electro-optic Q-switched laser devices that can only work in a low repeat frequency state, the electro-optic Q-switched pulse laser device in the invention can not only work in a low repeat frequency state, but also can work in a high repeat frequency state in a short period of time; and the repeat frequencies are in a large range and can be adjusted.

Methods and systems are provided to reduce stimulated Brillouin scattering in high power optical fiber amplifiers. In an embodiment, a seed source includes a narrow linewidth semiconductor laser driven with a current ramp that simultaneously sweeps the optical power and the lasing frequency at a rate fast enough to reduce stimulated Brillouin scattering.

A gyroscope includes drive electrodes that drive a drive mass at a drive frequency. A sense mass is responsive to a Coriolis force caused by rotation of the gyroscope and oscillates based on the drive frequency. Electrodes adjacent to the sense mass drive the sense mass at test frequencies. The response to the driving at the test frequencies is measured and a gyroscope failure is identified based on this response.

The invention provides a method for setting the rotating speed of a fan by utilizing RC frequency. A control chip sets the frequency range by utilizing at least one oscillator which is provided with at least one resistance element and at least one capacitance element. When the rotating speed of the fan is set, the resistance element and the capacitance element set the frequency and generate a pulse signal, a clock pulse generator converts the pulse signal into a square wave signal, a pulse sampler receives the square wave signal and judges whether the frequency of the square wave signal is lower than that of the control chip or not, if so, the pulse sampler receives a pulse signal which is generated by a frequency doubling signal generated by a high-speed clock device after doubling the frequency of the square wave signal, a multiplying unit receives the pulse signal to be converted into the frequency set by the rotating speed and generates a control signal, and a control unit controls the operation of the fan according to the control signal so as to achieve the purpose of setting the rotating speed of the fan.

A normally opaque waveguide interacting with a drop-filter cavity can be switched to a transparent state when the drop filter is also coupled to a dipole. This dipole induced transparency may be obtained even when the vacuum Rabi frequency of the dipole is much less than the cavity decay rate. The condition for transparency is a large Purcell factor. Dipole induced transparency can be used in quantum repeaters for long distance quantum communication.

The present invention provides an EIT-based photonic logic gate, which is constituted by EIT-based stack layers of periodic array of photonic crystal (PCs) layers and EIT (Electromagnetic Induced Transparent) material layers. The input probe signals are incident on the first photonic crystal layer, passing through one or more than one PCs-EIT interfaces and transmitted out from the last EIT material layer. Control filed as the enable signals are incident on each EIT layer to activate the optical logic gate. By varying the detune frequency of probe field and Rabi frequency of control field, its band gap structure can be adjusted. Henceforth, the tunable optical EIT-based photonic logic gate can be achieved as user required.

Frequency response is characterized for mechanical components of a multirate system operating in a closed-loop environment. A disturbance is injected at the frequency of interest and at each of the alias frequencies thereof as an input into the multirate system, and a matrix equation composed of resulting measurements of the response of the multirate system is solved to compute the frequency response at the frequency of interest and at each of the alias frequencies. The resulting frequency response can be used to synthesize the transfer function of the entire system, which allows simulation and evaluation of the relative performance of multiple controller designs without the need for further frequency response measurements.

The invention discloses a synchronization self-adaptation short-wave communication frequency-selecting method based on ionized layer data. The synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data comprises the step one that the maximum usable frequency of a channel is obtained by utilizing the ionized layer data according to short-wave communication link timing, wherein the ionized layer data comprise real-time observational data, historical data and the like; the step two that the range of usable frequency is determined according to the maximum usable frequency and by combining communication efficiency and / or duration of passable frequency; the step three that the range of the usable frequency is sent to a synchronization self-adaptation short-wave communication system; the step four that the synchronization self-adaptation short-wave communication system obtains the optimum usable frequency by scanning the range of usable frequency in a synchronization self-adaptation frequency-selecting mode, and then communication can be carried out. The synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data can overcome the defect in the prior art that the efficiency is low or it is difficult to obtain the optimum usable frequency due to the fact that channel information needs to be set in advance, and can efficiently select the optimum communication frequency. Thus, the synchronization self-adaptation short-wave communication frequency-selecting method based on the ionized layer data has an obvious effect on improvement of comprehension effectiveness of short-wave data communication.

A quantum power sensor comprising a two-level quantum system strongly coupled to a transmission line that supports a propagating wave. A method of measuring power in a transmission line, the method comprising: coupling a two-level quantum system to the transmission line; and determining the coupling and the Rabi frequency of the two-level system.

The invention relates to a novel photoelectron functional material, a growth method and an application, in particular to alkali earth metal fluoborite compounds as well as a crystal, a preparation method and an application thereof. The invention provides two alkali earth metal fluoborite compounds with the chemical formulas of CaB5O7F3 and SrB5O7F3 as well as nonlinear optical crystals, a preparation method and an application of the compounds. The CaB5O7F3 and SrB5O7F3 crystals can realize double frequency of Nd:YAG (lambda is equal to 1.064 mu m), and it can be predicted that CaB5O7F3 and SrB5O7F3 can be used for harmonic generators of triple frequency, fourfold frequency, fivefold frequency and sixfold frequency of Nd:YAG and even can be used for producing harmonic light with the wavelength shorter than 200 nm for output. The obtained CaB5O7F3 and SrB5O7F3 monocrystals are colorless, transparent, not prone to deliquescence and good in chemical stability. Predictably, CaB5O7F3 and SrB5O7F3 will be widely applied in various non-linear optical fields and non-linear optical application of deep ultraviolet bands will be opened up.

The invention relates to a Ka frequency range miniaturization broadband multimode auto-tracking feed source network. Two polarization degenerate modes of TE21 mode transmitted by center circular waveguide are coupled to four rectangular waveguide by adopting a four-arm circular polarization TE21 coupler. Two four-way polarization degenerate modes of the TE21 mode is combined into two two-way polarization degenerate modes of the TE21 mode by two broadband magic Ts. A left-handed or right-handed circular polarization difference mode is output by a broadband 90-degree electrical bridge. The TE21 coupler center circular waveguide is capable of simultaneously transmitting a TE11 mode. Due to the fact that the TE21 coupler is connected with a broadband circular polarization machine, and two polarization modes of a signal are respectively output from two ports of the broadband circular polarization machine, the Ka frequency range miniaturization broadband multimode auto-tracking feed source network is capable of simultaneously receiving a signal of double-circular polarization and a difference signal, and thereby the auto-tracking function is realized. The Ka frequency range miniaturization broadband multimode auto-tracking feed source network has the advantages of not only simplifying composition of the feed source network, reducing the volume and the weight of the whole device, but also reducing network construction, saving feed source cost and broadening working band of the feed source network.

Embodiments of the present invention provide a waveguide plasma limiter and a design method thereof, which relate to the field of electromagnetic pulse protection and can effectively resist high-power microwave weapons. The design method includes: determining the cut-off frequency fc and cross-sectional dimensions a, b of the rectangular waveguide according to the frequency f of the normal transmission signal, wherein fc=0.9f, b=0.3a-0.5a; determining the plasma frequency fp is less than the cut-off frequency fc is greater than the high-power microwave frequency fHPM, and the filling gas and the gas pressure of the filling gas under the condition of t<tr; the thickness of the filling gas is calculated

The invention provides a method for pre-stack CRP trace gather frequency-broadening processing. The method can maintain a good signal to noise ratio while improving the resolution of a seismic time profile according to spectrum characteristics of seismic waves, and can enable the resolution and the signal to noise ratio to be well combined. The method comprises the following steps of step one: using logging information and seismic traces by a well to perform inversion of a target layer section; step two: calculating a seismic wavelet according to the target layer number in the step one; step three: calculating the energy and frequency distribution range of an initial CRP trace gather; step four: obtaining the type of noise according to the energy and frequency distribution range of the initial CRP trace gather; step five: selecting a typical trace and determining an effective wave main energy distribution space; step six: determining a CRP frequency-broadening operator according to the energy and frequency distribution range of the initial CRP trace gather and the effective wave main energy distribution space; and step seven: performing CRP trace gather frequency-broadening processing according to the seismic wavelet, the type of noise and the CRP frequency-broadening operator. The method can maintain a good signal to noise ratio, and is high in reliability, good in stability and substantial in effect.